This invention relates to an optical tracking system for establishing a line of sight in accordance with a position command signal and, more particularly, to an arrangement in such a system for stabilizing the line of sight by moving a mirror to nullify vibrational effects.
U.S. Pat. No. 4,881,800, the contents of which are hereby incorporated by reference herein, discloses an optical tracking and stabilization system for use in an aircraft vehicle which tracks the movement of the pilot's helmet by developing a position command signal which causes the line of sight of the optical system to follow the line of sight of the pilot. In the disclosed system, a mirror is flexibly mounted to a rigid block which in turn is fixedly mounted to the inner gimbal of a pair of gimbals. A gyroscope having a spin axis aligned with the line of sight of the optical system is mounted to the rigid block to develop signals which are utilized to control movement of the mirror relative to the rigid block so as to nullify vibrations which emanate both from the gimbal system during its positioning of the rigid block and from the vehicle.
While the system disclosed in the aforereferenced patent is effective for its intended purpose, if in a particular application the optical system is subject to negligible aircraft vibration, the gyroscope becomes unnecessary. It is therefore an object of the present invention to provide a stabilization system of the type described in an environment where aircraft vibration can be ignored.
It is a more specific object of this invention to provide such a system which does not utilize a gyroscope.
It is a further object of this invention to provide such a stabilization system in an optical tracking system utilizing a pair of non-orthogonal gimbals.